Shulou(Shulou.com)06/02 Report--

Mike Gancarz

1.Unix development based on Multics time-sharing operating system

2.NIH (Not invented here, not invented by me)

3.GPL:GUN Public license Agreement, a legal agreement applicable to software. Open source

4.Unix philosophy:

1) small is beauty: easy to understand, maintain, low consumption of system resources, easy to combine with other tools

2) Let each program make one thing well.

3) establish a prototype (prototyping) as soon as possible: the concept of "the third system"

4) give up efficiency and portability

5) use plain text files to store data: binary is strictly prohibited

6) make full use of the leverage of software: borrow code modules; automate everything

7) use shell scripts to improve leverage and portability

8) avoid mandatory user interfaces

9) make every program a filter

5.Unix Creed

1) allow users to set the environment: the program should be a problem-solving mechanism, not a qualifying standard

2) make the operating system kernel small and lightweight as far as possible

3) use lowercase letters and keep them short

4) protecting trees: online storage

5) Silence is golden: when you need to provide error information, the unix command does not prompt

6) parallel thinking: most tasks can be broken down into smaller subtasks and run in parallel-symmetric processing (SMP) design

7) the value of each part is greater than that of the whole: Mini Program can be collected instead of large programs, which is flexible and practical

8) find a 90% solution: completing 90% will be more effective and cost-effective, and it is difficult to be perfect

9) worse is better: tolerance

10) hierarchical thinking: directory structure

6.MIPS Metrics: a popular way to measure CPU performance by executing tens of thousands of instructions per minute

7.IDE (interactive development environment) interactive development environment

8. Micro-optimizations: prof and other * * to locate the most frequently used subroutines to optimize the C language under unix

Description of tools and functions commonly used in 9.Unix-each command is actually a tool function:

1) awk: manipulate text organized by fields

2) expand: convert tabs to spaces

3) wc: calculate the number of lines, words and bytes of a file

4) sed: a non-interactive text editor

5) roff: a comprehensive text formatting and typesetting tool

6) tset: compare whether two strings are the same; check the mode of the file to see if they are writable

10. Unix stores the data as text, and then uses small tools to process the data with different faces and text.

11. A Shell script consists of one or more statements that perform tasks by calling local programs, interpreters, and other shell scripts. Each command is loaded into memory for execution, and these production programs are called indirectly.

Shell scripts integrate the efforts of others and fill your own goals.

Shell interpretive language, thinking-Editing-testing

Shell scripts cannot be used in the kernel.

12. One of the advantages of Unix philosophy is that it attaches great importance to a large number of small commands, and shell scripts are a way to unify them into a powerful whole medium.

13.CUI: a mode of interacting with an application, on top of the system's highest-level command interpreter. Once a program is called in the command interpreter, you can no longer interact with the command interpreter until you exit. The actual effect is that you are completely involved in the user interface of the application and will not be free until you exit.

14. Unix features: simplicity, correctness, consistency, integrity

15.VMS: closed source proprietary operating system, DEC. Basic belief: users are afraid of computers

The 16.VMS system is indeed the opposite of Unix.

VMS usually only provides users with a single solution path, while Unix provides a dozen or more solutions.

VMS systems like to use single programs with multiple options and large scale to meet the needs of many users. Small Unix is beautiful, each performing a single function and only a few options.

VMS originally used assembly language and BLISS-32, which is highly related to the underlying hardware structure. Unix adopts C language and is portable to many CPU architectures.

17.MS-DOS: an operating system designed for the public and easy to use. Concise and effective command language. It does not provide true multitasking, and it can only execute one command at a time, no matter how many commands are entered on the command line

18.Windows: design ideas are easier for beginners to use

19. Windows's graphical user interface is closely integrated with the underlying operating system, but X Windows System in Linux is essentially different from Windows: it is just an application running on an operation.

20. Almost all Perl (Practical and Report Language practical excerpt and reporting language) programs act as filters: very good at interacting with other software, obscure and difficult to use, extensibility, open source scripting tools.

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